The present invention relates to substrate processing (e.g., semiconductor device fabrication, flat panel display fabrication, etc.) and more specifically to a method and apparatus for orienting substrates (e.g., semiconductor wafers, glass substrates for flat panel displays, etc.).
Proper alignment or xe2x80x9corientationxe2x80x9d of substrates is often required during substrate processing. For example, proper semiconductor wafer orientation is required during processing steps sensitive to wafer orientation (e.g., lithographic processes, masking steps, etc), for reading information scribed on a wafer""s backside (e.g., lot number wafer serial number, etc.) and the like. Accordingly, to identify wafer orientation, semiconductor wafers are provided with a flattened edge region termed a xe2x80x9cflatxe2x80x9d along an otherwise rounded wafer edge, or a small portion of a wafer""s edge is removed to form a xe2x80x9cnotchxe2x80x9d therein.
Conventional wafer orientation devices typically comprise a platform having a rotatable surface, and a wafer orientation sensor (e.g., an optical sensor) positioned a small distance above the platform. To achieve a desired wafer orientation, a wafer is placed on the rotatable surface of the platform, the rotatable surface is rotated (so as to rotate the wafer) and the wafer position sensor is employed to identify when a flat or notch of the wafer is in a predetermined position. The wafer position sensor then transmits this information to the platform to cease wafer rotation. Accordingly, wafer transfer to, wafer orientation by, and wafer transfer from conventional wafer orienting devices follows the same sequence: 1) a wafer handler extracts a first wafer from a multi-slot wafer carrier and transports the first wafer to the wafer orienting device; 2) the wafer orienting device orients the first wafer; and 3) the wafer handler returns the oriented first wafer to the multi-slot wafer carrier. Thereafter the sequence repeats and the wafer handler extracts a second wafer from the multi-slot wafer carrier and transports the second wafer to the wafer orienting device, etc.
As indicated by the sequence described above, conventional wafer orienting devices allow only one wafer to be oriented at a time. Such operation reduces throughput and increases wafer processing costs. Further, expensive and large footprint orienting equipment (e.g., a separate wafer platform, a motor required for rotation thereof, etc.) is also required. Accordingly a need exists for an improved wafer orienting device.
To address the needs of the prior art, a wafer orienter is provided that can simultaneously orient multiple substrates while occupying a small footprint. A small footprint preferably is achieved primarily by employing equipment already present within most device fabrication tools (e.g., so that the equipment does not consume any additional space) and by implementing the orienter in a compact, vertically stacked configuration. Simultaneous substrate orientation significantly increases substrate throughput, thereby decreasing cost per unit substrate processed. A small footprint further decreases cost per unit substrate processed by reducing cleanroom space requirements.
In accordance with the present invention, a multiple substrate orienter is provided that includes a rotatable substrate handler having a plurality of substrate support portions, each adapted to support a substrate. The multiple substrate orienter also includes a plurality of stacked substrate-supports, each adapted to support a substrate. A plurality of substrate orientation marking (SOM) detectors are provided, and each SOM detector is coupled to a different one of the substrate supports and is adapted to identify a presence of an SOM (e.g., a wafer flat or notch) of a substrate positioned close enough to the SOM detector to allow SOM detection by the SOM detector. The multiple substrate orienter further includes a plurality of lift and lower mechanisms, each lift and lower mechanism coupled to a different one of the substrate supports and adapted to individually lift and lower the substrate support to which the lift and lower mechanism is coupled. Alternatively, each lift and lower mechanism may be coupled to a different one of the substrate support portions of the rotatable substrate handler and adapted to individually lift and lower the substrate support portion to which the lift and lower mechanism is coupled.
Preferably the multiple substrate orienter includes a controller coupled to the rotatable substrate handler, to the plurality of SOM detectors and to the plurality of lift and lower mechanisms. The controller preferably has program code adapted to simultaneously rough orient a plurality of substrates loaded onto the substrate support portions of the rotatable substrate handler, and to individually fine orient each rough oriented substrate. As used herein, to xe2x80x9csimultaneously rough orient a plurality of substratesxe2x80x9d means to perform at least one portion of a rough orientation process simultaneously on the plurality of substrates, although each and every portion of the rough orientation process need not be performed simultaneously on all of the substrates. To xe2x80x9cindividually fine orient each rough oriented substratexe2x80x9d means to fine orient each rough oriented substrate one substrate at a time (e.g., not simultaneously).
In another aspect of the invention, a substrate orienter is provided the rotatable substrate handler of which has a single substrate support portion adapted to support a single substrate. Both aspects of the invention employ the substrate handler""s rotational capability for substrate orienting, and both aspects perform a high speed rough orient which considerably reduces the time required for substrate orienting, as compared to conventional methods.
Other objects, features and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiments, the appended claims and the accompanying drawings.